CVE-2009-4445

Microsoft Internet Information Services (IIS), when used in conjunction with unspecified third-party upload applications, allows remote attackers to create empty files with arbitrary extensions via a filename containing an initial extension followed by a : (colon) and a safe extension, as demonstrated by an upload of a .asp:.jpg file that results in creation of an empty .asp file, related to support for the NTFS Alternate Data Streams (ADS) filename syntax. NOTE: it could be argued that this is a vulnerability in the third-party product, not IIS, because the third-party product should be applying its extension restrictions to the portion of the filename before the colon.

Published: 2009-12-29 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2009-4445 is rated Moderate Risk (60.2/100): CVSS Medium severity, with high exploitation likelihood (EPSS 12.76%, 96th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +2.70% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2009-4445

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 10.06% 12.76% +2.70%
2 2025-12-28 14.77% 10.06% -4.71%
3 2025-12-27 — 14.77% —

Full EPSS history (21 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2009-4445

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.0 2.0 MEDIUM
AV:N/AC:M/Au:S/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.8 6.4 [email protected]

Weakness enumeration for CVE-2009-4445

Affected software / configurations for CVE-2009-4445

Vendor Product Version Raw CPE
microsoft internet_information_services <= 6.0 cpe:2.3:a:microsoft:internet_information_services:*:*:*:*:*:*:*:*

References for CVE-2009-4445

cvelogic Threat Intelligence